F9 and F91 steel for low temp

[Johnwoo1991]

Is it true that high alloyed F9 and F91 grades become easily brittle at 0°C or even at ambient temperature?

Is it the same even for low alloy F11 and F22 steels?

 

[EdStainless]

There is a ton of data out there on this.
P9 and 91 will have lower ductility at low temperatures than less alloyed steels.
How low depends on how they were heat treated.